Good afternoon, all so i've been doing some more work on my evse pcb. This is the printed circuit board for my electric vehicle supply equipment, um, which is going to replace the pcb in the evse that i bought. This is going to be a much simpler version. Now you can see that i got my input.

Connector here live earth and neutral got two of these relays. I'll probably go for the ones. Without these spade terminals, on the top initially and here's my output connector live. Oh, what would be earth? This is control pilot.

I think the third one down and neutral at the bottom um i've got my mains to 12 volt power supply. Although there is a bit of an issue with this and i'm thinking of switching to another one, i put a fuse in there as well, because i figure this power supply should be fused protected from powerful mains. That's sitting across here and of course i need minus 12 volts, so this is a little dc to dc converter isolated. So you can connect the positive of this to the negative of this one and that will give you minus 12 volts.

So that means i've got plus and minus 12 volts now down here. There's a patch area with lots of these six actually of these 16-pin duel in line arrays with a couple of extended out pad areas so that i can do all my wiring up for the analog and cmos digital circuitry in this area. But i didn't want to sort of carry on designing the schematic at this point, because i want to do that kind of interactively on video with you guys, so i will be patching all the circuitry down in this area. Now you may have noticed that these barrier terminal strips look a bit odd and that's because there's actually two different types of terminal strip, which is why you can see sort of two sets of screws there kind of sort of sitting in the same place on the Board and that's because it looks like it might be quite difficult to get these 9.5 millimeter pitch strips so in the same footprint, and you can probably see this better in the pcb layout here.

I've put some 8.5. This is the smaller footprint here. 8.5 millimeter pitch terminal strips which have an offset row of uh pins in the footprint i've put them sort of roughly in the same place, but it means i've got these two sets of connections. I can use either connector because i just want to make it a bit more flexible in case i can't get the 9 the big one here, the 9.5 millimeter pitch sockets, i might have to use the other one.

So here are the patch areas you can see fuse there power supply. Now on this power supply. There is a bit of an issue. So here's the data sheet for this high link: 3 watt 12 volt.

The pm12 is 12 volt, ultra small power supply module. But when i looked through this data sheet down to here for the typical application circuit external to the psu module, you have to have a common mode, choke and a class x mains voltage, capacitor 100 n and they recommend a varistor there and a fuse. So a whole bunch of the components you'd expect to be inside this module in addition to a output, smoothing capacitor simply aren't in that module. So i'm not really sure this is what i want, because i really wanted everything to be integrated into this box so that if you accidentally touch it, it's fully integrated and sealed you don't get a shock off it.

Well, if you're gon na have to have external components on the main side, there's not much point using this module. So i'm thinking i might go for something like this, which is an open, um, psu module. This one is 12 volts, half an amp, but i mean you can see on there that you've got oh well. Actually this one, i'm not so sure, but there looks like there's a choke there common mode, i presume uh, don't see a fuse on there.

So i'll probably keep that external fuse, but is there a mauve i can't see a mob on there either, but um certainly most of the components that you'd want on here, including the smoothing caps on the output side. Here are included on this module. So i might just stick this module hover it above the pcb and just solder it through with wires on these pin pads here so yeah, certainly looking at something like this, it's a little bit cheaper as well than the fully self-contained sealed module. So certainly looking at that as an alternative um and it's a little bit bigger than the self-contained module, i presume because it's got those extra components on the board and the spacing here on the main side is probably about the same.

But it will extend out here to the left, with two pins quite close to each other. So what i was thinking was putting a capacitor here and then, instead of fitting that capacitor, you could actually use it as two holes to suspend the larger module, which will sort of come out to here from this main side down to this 12 volt side. At this end, so give me the option to use the original psu well, it wouldn't actually because i wouldn't have the uh choke and varista on on the main side. So yes, this would then be the footprint for i i could draw a new footprint for that.

Psu, but it would mean waiting until i get it, so i think i'm just gon na roughly place the holes here and if the psu has to sit above this with the worst bent at funny, angles doesn't really matter to me as long as i can get It on the board and get my 12 volts down onto this board and start wiring up my cmos logic and comparators in this patch bay area. Now i just wanted to show what i've done on the high current connections here between the two options for barrier strip terminals and the relay. So this is mains in going off to the two relays: mains and alive and neutral through the relays and into the output barrier strip it's. This is all it is, it's inputs relays, outputs, and this is protective earth and i've put a fairly small track on protective earth, because the evsc i took apart had a very small track.

I don't think the protective earth is intended to take the full current of live or neutral down to earth. I don't think that's the purpose of it so, but i've just followed what i saw on the other ebsc, but i just wanted to show what i've done on these. You can see. I've got fat, they're, five millimeter top side tracks.

If i turn off the top layer, you can see that i've also got fat. Five millimeter bottom side tracks. But if i turn off the bottom layer, you can also see that i've got these three millimeter um tracks again the same position tracks, but on the bottom solder mask layer and i'll show you uh the purpose of that on a 2d view of the printed circuit Board, so here you can see on the top side, we've got nice fat tracks, linking the terminal strips to the relays and on the bottom side, um we've got similar fat tracks, but by putting the tracks also three millimeter. These are five millimeter big ones, but by putting three millimeter um tracks on the solder resist the bottom solder resist you can see, it's actually cut out a section of solder resist, and it gives me some bare, copper and my aim.

There is to run possibly just a piece of tin, copper wire across there and then flood it with solder to provide high current bottom tracks, but also have those tracks on the top side as well. So we get the best possible current handling capability between the terminal. Strips and the relays, and finally there's this: this is a a 12 volt to 12 volt, isolated, miniature uh dc to dc converter. Now you might think, what's the point in converting 12 volts to 12 volts? Well, because this is isolated, you can hook up the or what would be the negative side of this.

No, the positive side of this to the negative side of the main 12 volt power supply, and that would give you a negative 12 volt power supply. And that gives me plus 12 volts minus 12 volts because, of course, the square wave which ultimately has to be routed out to this position. Here, the cp, the control pilot out to the car, has to have this positive, going 12 volts and negative, going 12 volts. Waveform uh, so we need some cluster oven.

We need some minus 12.. So that's what that little four pin device is now there's a little bit more work to be done on this. I need to put some capacitors on here and also roots and power lines over here near these patch areas put some plus 12 volt and some minus 12 volt into these areas, so that i can start patching components into this proto area um. I need some relay drivers, they're fairly standard bipolar transistors, with the diode to um sort of squash out the back emf when these things open up uh resistor on the base of the uh transistor.

So a couple of i'll probably implement those as a surface mount. I like to do a little bit of these uh surface, mount assembly service components on these pcbs. So i will probably put those on the top here of the board, but that's close to being finished and then i'll send this one away and when i get it back, we can start working on the logic of this circuit, which i'll go into a little bit Of an explanation now so this is a web page, uh called analog evse, and this is pretty much what i want for my first version: basic analog, um, it's not j1772. In the uk, it's slightly different in the uk.

It's a different number. I can't quite remember what it is, but this is um, this guy's board and its comparators and some cmos logic. There's a crystal. There he's got crystal timing and i'll just switch now to the uh schematic, which is this, and you can see that this is consists of these comparators to do things like the voltage measurements to measure uh when the 12 volts gets pulled down to 9 volts when It gets pulled down to 6 volts.

There is an option for it to be pulled down to 3 volts. That means charging has to take place in a ventilated area. It's a bit of a legacy thing for cars that have lead acid batteries. It's not really used these days.

Um, you can see. He's got a cmos 4060 clock generator with a crystal circuit here to generate a fairly precise timing for this one kilohertz uh square wave uh. I might do this slightly differently. He's got a comparator here chopping.

The well he's turn the square wave into a sort of triangle, wave it's more of a analog triangle wave and then he clips it with this comparator and it's voltage controlled. I probably won't do that because i don't want voltage control in the timing parts of the circuitry, but essentially i'm going to copy this system now. This is open source hardware. There is a copyright notice here, um here, copyright, bernhard volta, so because this page is copyright, i've contacted bernhardt and he's quite happy for me to use this circuitry.

It is open source. So that's fine and also um show the page here, despite it being copyright. So we've had that discussion, i'm going to go ahead. Use large parts of this circuitry make some small changes to it to suit myself.

But essentially, this is what i'm going to be using as the basis of my first version evse, which has no microcontroller and then later on. I will go to an arduino-based evse, because the thing i particularly want is to be able for the arduino to receive data from my rooftop solar system so that the charging of the car can occur at the same power level as what's coming off the roof. And therefore there needs to be a communication of available rooftop solar power. So that's where i've got to so far with the evse project.

Now, if you're wondering why i'm bothering to make an all analog or sort of comparators and cmos logic version prior to getting onto an arduino version? Well, really it's about having a system which is easy to see how it works. The whole point about evse the spec, for it is that it was designed to be very simple and able to be built without programmed components. So, yes, i'm going to build one without programmed components to start with, so that we can all see how it works. How the the um sequencing works? It's not really sequencing.

It's just responding to various states of the control pilot signal, uh. What the timings are? There really aren't any timings in the evse itself. The car might the car's own inbuilt charger might do various timings, but that's why i want to do this as a two-step project, and you know having a patch area here and building comparators and cmos logic. It's a bit more visual than just doing software on screen.

So hopefully, we'll see a bit more about how this thing works, but that's how far this has progressed so far. I'm gon na continue working on it, but for this video, that's about it so cheerio.